Beretta 92FS - my first firearm purchased back in 80s - bought it because of Lethal Weapon/Mel Gibson.
Beretta is one of the most famous firearm in movie (right next to Glock 17). 周潤發's favor firearm in 吳宇森 movies. Not everyone like it because of the grip size but it was the standard sidearm for US military in 80s/90s.
The different between the common G17 vs. G34 are the barrel length and the trigger pull. G34 is designed to use out-the-box for USPSA/IPSC in Production class. 9 mm with 17 rounds mag (I bought mine in US before the band). Nice and cheap.
Glock 21 is in .45 ACP - recoil is much heavier compare to the G34.
I have also replace the stock slide with a Lonewolf custom + 6" barrel + redot sight.
Average AR here is US is at around $1500 +/- $500. They all do the function - just like buying a Honda vs. Lexus - get you from A to B, just with the fancy package.
My STI is not that bad, cost at around USD $3000 (it has custom trigger and everything else). Some of the Open gun cost much, much more (USD $5k and up - plus 1 to 2 year wait time).
I guess it is the supply/demand market here in US. Buying a gun is easier than buying a car.
You can get a low end cheap cheap .22 for less than USD $100 brand new. A clone AR type rifle for less than $500. When I visited HK and look at all the air-soft at Kwong Wa Street - they are so damn expensive! I can get a real pistol (Glock, 1911 or Beretta) for the same/or similar price here in US!!